There was a recent thread entitled 'Remember These?' , which seems to have run its distance, about the 'No 8' 3 Volt battery. I didn’t contribute to that thread, but coincidentally, a little signal injector I’ve had for more than 20 years, which uses a No 8 battery, died on me last week. I took the injector lid off, and found a little note I’d put inside stating that the battery was installed in May 1997, and cost of 85p!
These once popular batteries, evocative of a bygone age, were used in small torches and in test equipment, but are now not stocked by high street shops, Maplin, Halfords etc.
They are however, still available via internet – the lowest price I can find being £3.45.
They've been known by a host of different numbers and are now known as 2R10, so anyone looking for a No 8 battery will have as much luck as asking for a ‘U2’ – a title which went out in the 1970s. (D Cells – AKA MN1300).
The 2R10 (or if you prefer, 'No 8') only has a capacity of 1000mAh, whereas a smaller lithium battery the CR123A has a capacity of 1.6Ah, so I decided to make an adaptor to use a CR123A in preference to a 2R10/No 8.
Luckily, 20mm plastic conduit has an internal diameter exactly the same size as a CR123A. All that was needed was a spacer, which I made from a piece of wood, drilled through the centre, with a brass cheese-head bolt, so that when assembled, it's the same length as a 2R10/No 8 - namely, 74.6mm.
The 2R10/No 8 battery is 21.8mm diameter – 1.8mm larger than 20mm plastic conduit, so for my requirements, 20mm diam was near enough – I’m only interested in functionality – not making an exact replica.
However, I know that there are those who do enjoy making replica batteries of the exact size, and there are two ways of doing this:
1) 20mm plastic conduit is an exact fit inside 22mm copper plumbing pipe, which is just 0.2mm (8 thou) diam larger than the 2R10/No 8, so a copper sleeve could be made from that pipe and slipped over the plastic conduit and glued in place, then a label affixed.
2) Thin card could be rolled around the conduit to bring the diameter up to 21.8mm and glued in place, then a battery label affixed.
I claim no originality for this idea – an easier option can be found here:
Make a replica size 8 3Volt battery:
http://highfieldsarc.6te.net/beginne...batts/2r10.htm
Or you can buy a 2R10/No8 from here at £3.45 each:
http://www.batterycity.co.uk/2r10__3...ry-p-3885.html
I bought two CR123A 1.6Ah lithium batteries for £4.75 (buy one/get one free) inc VAT and P&P from here:
http://www.toptechbattery.co.uk/
A useful website for reference purposes – it illustrates a whole range of batteries and cells, and their dimensions and specifications.
I don’t have any connections with any of the above, or indeed any commercial organisations except as a satisfied customer.
I’ve attached some pics which illustrate the adaptor I made, it its new home!
There are other (cheaper) options - A card of two Type N (LR1) 1.5V alkaline batteries, (though not as high a capacity as the lithium 1.6Ah CR123), typically cost less than a pound.
LR1s are 10mm diam and 30mm long each, so that's 60mm the pair. All that would be needed would be a 14.6mm spacer to make up the length, and a wooden rod 20mm diam, drilled through 10mm to insert the batteries into a piece of 20mm plastic conduit.
The first pic shows the component parts, the second shows the battery, wooden spacer with with the bolt in place, the final pic shows the battery in situ.
David,
G4EBT